Light-emitting devices such as vertical-cavity surface-emitting lasers (VCSELs) are known in the art. In general, a VCSEL will employ one or more quantum wells to capture and confine carriers (electrons or holes), which subsequently radiatively recombine to generate light.
Contemporary VCSELs generate light having a wavelength in the range of approximately 850-980 nanometers (nm). The ability to generate light at longer wavelengths is advantageous, especially in optical communications, and development of VCSELs that generate light at wavelengths of 1200 nm or more is ongoing. One type of longer-wavelength VCSEL includes an active region that incorporates a quantum well structure composed of one or more quantum well layers of indium gallium arsenide nitride (InGaAsN) and a corresponding number of barrier layers of gallium arsenide (GaAs). The quantum well(s) defined by the quantum well structure have a depth on the order of 300 meV (millielectron volts).
A problem associated with the longer-wavelength VCSEL just described is that the characteristic temperature (T0) and the differential quantum efficiency (η) are lower than expected, particularly under conditions of high carrier injection and especially considering the depth of the quantum wells.
Accordingly, solutions that increase the characteristic temperature and the differential quantum efficiency are sought.